Rename the coins folder to networks

Ethereum isn't a coin. It's a network.

Resolves #357.

networks/bitcoin/tests/rpc.rs

@@ -0,0 +1,25 @@
+use bitcoin_serai::{bitcoin::hashes::Hash as HashTrait, rpc::RpcError};
+
+mod runner;
+use runner::rpc;
+
+async_sequential! {
+  async fn test_rpc() {
+    let rpc = rpc().await;
+
+    // Test get_latest_block_number and get_block_hash by round tripping them
+    let latest = rpc.get_latest_block_number().await.unwrap();
+    let hash = rpc.get_block_hash(latest).await.unwrap();
+    assert_eq!(rpc.get_block_number(&hash).await.unwrap(), latest);
+
+    // Test this actually is the latest block number by checking asking for the next block's errors
+    assert!(matches!(rpc.get_block_hash(latest + 1).await, Err(RpcError::RequestError(_))));
+
+    // Test get_block by checking the received block's hash matches the request
+    let block = rpc.get_block(&hash).await.unwrap();
+    // Hashes are stored in reverse. It's bs from Satoshi
+    let mut block_hash = *block.block_hash().as_raw_hash().as_byte_array();
+    block_hash.reverse();
+    assert_eq!(hash, block_hash);
+  }
+}